Process for treating primarily metallic materials



p 12, 1967 T. w. MbRmsoN ETAL 3,341,321

FROCEFSS FOR TREATING PRIMARILY METALLIC MATERIALS Filed Oct. 9, 1963POWER 7 //2 SOURCE as; AND

CONTROL /0 PANEL VACUUM SYSTEM WATER OUT Z6 WATER IN V mvem'ons THOMASWMORR SON HARRY O. WALP United States Patent ()fifice 3,341,321 PatentedSept. 12, 1967 Vania Filed Oct. 9, 1963, Ser. No. 315,086 5 Claims. (CL75--12) This invention relates to processes for treating primarilymetallic materials, including metal alloys, to control and improve thecharacteristics thereof, and particularly to processes for providingimproved rolling-bearing materials and elements. In a more specificaspect it is especially concerned with producing ferrous alloys, androlling-bean ing elements such as race rings and balls made therefrom,which are characterized by longer fatigue life.

In the production of metals it is common to produce an original bodycomprising metal desirable elements which it is intended to provide inthe final metal product, which body however is often of inadequatequality and improper shape and form for a given application. Forexample, the original body may be an air-cast ingot poured from moltenmetal in a conventional arc furnace, or it may be formed of sponge orfrom sintered or compressed materials having undesirable e.g., gas. Thelatter process has been applied to a number of different metals, such asferrous alloys, niobium, molybdenum, titanium, zirconium, high-meltingnickel and cobalt base alloys, and numerous other mate rials, and hasproved satisfactory for many purposes.

However, it has been found that ingots produced by consumable-electrodearc melting in an inert environment, as previously practiced, generallycontain a substantial number of so-called non-metallic inclusions, whichcomprise small localized regions in the ingot having a compositiondiffering drastically from the desired average composition of the ingot.For example, in an ingot of a ferrous alloy these inclusions maycomprise aluminates, silicates, nitrides and sulfides. Furthermore,these nonmetallic inclusions tend to be non-uniformly dispersed throughthe ingot, especially Where the original metal body was formed byordinary air casting. The presence of such non-metallic inclusions insubstantial sizes and numbers per cubic centimeter, as well as theirnon-uniform dispersion through the ingot, are known to comprise a sourceof degradation in the quality and reproducibility of the characteristicsof the ingot, to a degree which is particularly important where themetal is to be used in special, critical applications.

One special application in which the quality and reproducibility of themetal is of great importance is in the field of ferrous alloy metals foruse as the load-bearing elements of rolling-bearing assemblies, forexample in the inner and outer races and in the balls of a ball-bearingassembly. In this application it is extremely important that the metalused have the greatest possible resistance to fatigue during normal use.

Resistance to fatigue in a device such as a roller and ball bearingassembly is commonly measured by a quantity known as fatigue life, whichis the amount of useful service, usually measured in bearingrevolutions, which can be obtained from the bearing under conditions inwhich the limiting phenomenon is metal fatigue in the bearing material.More particularly, if a bearing is effectively protected from moisture,dirt, etc., is well lubricated and is otherwise properly handled, allcauses of damage are eliminated except one, namely the fatigue of thematerial from which the bearing is formed, due to repeated stressesthereon during rotation. The effect of such fatigue is generally toproduce a spalled area on one or more of the load-carrying surfaces ofthe bearing assembly, and the number of revolutions of the bearingrequired to produce such a spalled area is a measure of the fatiguelife. Obviously, it is desirable that the fatigue life be as long aspossible.

While the fatigue life of an individual bearing is easily measured bythe abovedescribed criterion, a statistical definition of fatigue lifebecomes necessary when the lives it is necessary to formulate a of theterm fatigue life for this purpose.

Accordingly, the term fatigue life as used hereinafter denotes thatnumber of bearing revolutions, which is successfully reached or exceededby a given percentage of the group of bearings tested. This fatigue lifeis designated by the letter L followed by a number sufiix; thus Lindicates that only 10% of a given lot of bearings have failed due tofatigue phenomena after a stated number of bearing revolutions, and Lindicates that only 50% have failed.

In the interest of increased service life and reliability, there haslong been a need to increase the resistance of a ings having highervalues of fatigue life L L etc. Copending application Ser. No. 250,507,of H. 0. Walp, filed Jan. 10, 1963, and entitled Ferrous Alloy, now US.Patent No. 3,249,427, discloses and claims a composition of ferrousalloy particularly suitable for providing rolling bearings of increasedfatigue life. However, it remains desirable to increase further thefatigue life of rolling-bearing elements made from this composition ofmetal, or from other compositions.

Accordingly, it is an object of the invention to provide a new andimproved process for the refinement of metalcontaining materials whichenhances the quality and reproducibility of metal bodies derivedtherefrom.

Another object is to provide a new and improved process for reducing thenon-metallic inclusion content of a body of metal.

A further object is to provide such a process which not only reduces thenon-metallic inclusion content but also provides a more homogeneousdistribution of any such inclusions which remain in the metal body.

A further object is to provide a process for reducing the non-metallicinclusion content and rendering it more homogeneously distributed, in ametal body produced by a consumable-electrode arc melting process.

It is also an object to provide the latter improvements where theconsumable-electrode of the consumable-electrode arc melting process isderived from an air-cast ingot of metal.

It is a further object to provide the above-mentioned improvements innon-metallic inclusion content and homogeneity in a ferrous alloy havinga composition particularly suited to produce long fatigue life in partsfor bearing assemblies.

Another object is to provide a process for producing a body of ferrousalloy characterized by a fatigue life which is greater than that ofalloys of substantially the same composition made by other processes.

It is also an object to provide a new and improved process forfabricating rolling-bearing elements of long fatigue life.

In accordance with the invention the above objects are achieved bysubjecting an original primarily metallic body to repeatedconsumable-electrode arc meltings in an inert environment, theconsumable-electrode for each melting after the first being derived fromthe lower portion of the ingot produced by the immediately precedingconsumableelectrode melting, thereby to provide a quality-enhancingmetal treatment of a highly advantageous nature. In particular, whensuch melting is applied repeatedly, for example at least three times andpreferably five times, the non-metallic inclusion content of the finalmetal ingot is greatly reduced, and the homogeneity of the material withrespect to non-metallic inclusions is also generally improved, ascompared with the original material and with material resulting from aconventional single consumableelectrode arc melting step. The reductionin the nonmetallic inclusion content is apparently due to flotation ofthe lighter material of the inclusions to the top of the melt, wherethey are then frozen into the top portion of the ingot which is laterdiscarded. Transformation of some of the material of the inclusions togaseous 'form and re moval of the so-evolved gas during the meltingsteps also contributes to the improvement in the metal.

We have further found that rolling-bearing elements of improved fatiguelife are obtained when they are made 4 from a ferrous alloy body whichhas been subjected to repeated consumable-electrode inert-environmentarc melting of the lower portions of the successively produced ingots.Particularly long fatigue lives are obtained when this repeatedconsumable-electrode inert-environment arc melting treatment is appliedto a starting body which is a ferrous alloy having substantially thecomposition described and claimed in said copending application and setforth in detail hereinafter. Preferably the repetitiveconsumable-electrode arc melting is applied five times in a vacuumenvironment, producing fatigue lives typically about three times as longas those obtained without consumable-electrode arc meltings and abouttwice as long as those obtained by a single consumable-electrode arcmelting.

Other objects and features of the invention will be more readilyappreciated from a consideration of the following detailed descriptiontaken in connection with the accompanying drawing, in which the singlefigure is a diagrammatic elevational view, partly in section, showingone form of conventional apparatus as it may be utilized in performingcertain steps in accordance with the invention.

The invention will first be described in a form in which it can be usedto provide ferrous alloy ingots suitable for use in rolling-bearingelements of increased fatigue life. For this purpose the startingmaterial is preferably an airmelt pre-cast ingot with any peripheralslag removed, shaped to suitable form for use as the cylindrical con- ACu Mo Ni 25 0.015 0.0e 0.04.0 0.0s0 0.

sumable-electrode 10 in the figure, and preferably having substantiallythe following composition:

Element: Percent by weight C (about) arbon 0.95 to 1.10 Chromnun 1.30 to1 60 Manganese 0.25 to 0:45 Silicon 0.20 to 0.35 Phosphorus Up to 0.025

Sulfur Do Aluminum Up to 0.015 Copper Up to 0.060 Molybdenum Up to 0.020Nickel Up to 0.080 Vanadium Up to 0.003 Iron Remainder.

the respective amounts of the elements aluminum, copalloy being such asto provide a value of not re t r than about 3.5 in the formula: g a eapplication and falling Within the composition formula set forth above;for example for best results the original material consistssubstantially of about 0.010% aluminum up to about 0.050% copper, up toabout 0.015% mo lybdenum, up to about 0.055% nickel and up to about0.002% vanadium, and the value of is preferably not greater than about 3.0.

This consumable-electrode is first subjected to a consumable-electrodeinert-environment are melting process. As indicated in the drawing, in atypical form of this 5 process the consumable electrode 10 having theabove composition is disposed in an electric furnace 12 with its aXlsvertical and its lower end adjacent, but spaced above a thermally andelectrically conductive ingot mold 14 which may be of copper, the mold14 being in thermal heat exchange relation with a cooling jacket 16through which cool water is circulated. An inert environment is providedin the furnace 12 by sealing it appropriately and connecting a vacuumsystem 18 thereto, although in some cases a sweep of an inert gas suchas argon, neon, helium,

or nitrogen may be provided through the furnace, instead.

A power source and control panel 20 applies electric potential betweenelectrode holder 22 and conductive mold 14, which are insulated fromeach other, and conventional means (not shown) are provided to moveelectrode holder 22 and hence consumable-electrode 10 along the verticalaxis in such a manner that an electric are discharge 24 is produced andmaintained, for as long a period as desired, between the lower end ofthe consumableelectrode 1-0 and the conductive mold 14 or the uppersurface of any metal which may be deposited therein in the course of theprocess. The current in the arc is suflicient to cause a progressivemelting of the lower end of the consumable-electrode 10 and a depositingof the resultant molten metal in mold 14 to form an ingot therein.

The forced cooling provided for mold 14 is such as to produce acontinuously upward-growing resolidified body 26 of deposited metalnearer the bottom of the mold, while the upper surface of the depositedmetal is continuously supplied by electrode 10 with new molten metalmaterial forming a molten pool 30. When the desired amount of consumableelectrode 1 has thus been melted and resolidified as a new ingot in themold, the electric current is terminated to permit resolidification toproceed to the uppermost portion of the ingot.

During the above-described consumable-electrode melting process, theamperage of the arc current is maintained sufiiciently high to assure acomplete melting of each increment of the consumable-electrode which isdeposited in the mold, and to assure that the so-deposited molten steelmetal is at a sufficiently high temperature to assure rapidintermingling of all of the constituents of the ferrous alloy and topermit undesired non-metallic inclusions to float to the surface of themolten pool. The cooling of mold 14 is sufficient to provide forresolidification of the metal deposited therein from the bottom upwardsas the process continues, while causing the molten metal pool 30 toremain at sufiicient volume and high enough temperature thatnewly-deposited metal remains molten long enough to insure its completeintermingling and homogenization with the molten metal of pool 30.However the cooling is sufiiciently great so that each added incrementof molten material does not remain in the liquid state long enough forundesirable separation or segregation of the constituents of the ferrousalloy to take place during resolidification.

Typically the temperature at the lower end of electrode during theprocess is between about 2600 and 8500 F., depending on the nature ofthe material, and the approximate melting rate of the ferrous alloy fora 2.5 ton furnace is from about 0.5 to 1 ton of ferrous alloy per hour.While outstanding results have been obtained by using a direct currentsupply for the arc, it is also possible to use alternating current orthe combination of alternating current superimposed upon a directcurrent component for this purpose. Apparatus and techniques forproviding the above-described consumable-electrode process are wellknown in the art and hence need not be described in further detailherein.

It has been found that, during the course of the abovedescribedconsumable-electrode inert-environment arc melting step, non-metallicinclusions originally present in the consumable-electrode and depositedin mold 14 in molten form tend to rise to the top of molten pool 30 thusproducing a heavy concentration of non-metallics at the upper end of theingot as represented by the heavy line 34 in the figure. The solidifiedingot which is the product of this procedure therefore contains asubstantial proportion of the non-metallic inclusions concentrated atits upper axial end. A minor amount of non-metallics is generally alsopresent in the form of a thin scale on the other surfaces of solidifiedingot. After the ingot is removed from mold 14 the peripheralnon-metallic regions are removed from the outer diameter of the ingot,as by machining or grinding. Except for the very top, the ingot then hasa substantially lower concentration of the undesired non-metallicinclusions. This top is discarded.

In addition, the mobility of the non-metallic inclusion material in themolten metal pool 30 during the arc melting process tends to produce amore homogeneous distribution of the remaining non-metallic inclusions,particularly in the direction transverse to the growth access of theingot. The resultant improvement in homogeneity in the ingot as comparedwith that in the consumableelectrode is particularly pronounced wherethe consumable-electrode was formed by ordinary air-melt techniques.

In addition, the use of an inert environment during theconsumable-electrode process not only prevents the formation of furtherundesired materials in the ingot, but also tends to remove dissolvedgases or other volatile substance originally present in theconsumable-electrode which otherwise would contribute toward porosity orimpurity of the solidified ingot. These gaseous substances becomerelatively highly volatile at the elevated temperatures produced duringthe process, and are sucked away by the vacuum or are swept away by theinert gas sweep. Where a vacuum is used, pressures from about 5 to about50 microns are preferred, although during the initial portion of theconsumable-electrode melting step the volatilization of gas may occur atsuch a high rate that it is impractical to maintain the pressure belowabout to 200 microns of mercury. This temporary rise in pressure is notharmful so long as it is brought down to the above-described lower levelduring the re mainder of the melting step. Where a gas sweep isemployed, super-atmospheric pressures are preferably employed, forexample from about 1 to 20 atmospheres.

Further in accordance with the invention, the lower portion of the ingotremaining after grinding away of its outer surface is remelted inanother consumable-electrode inert-environment arc melting processsubstantially the same as that described above, and the finished ingotresulting from this melting step is again machined or ground to removeperipheral slag portions and the remainder used again as aconsumable-electrode in a similar melting step. In each case the upperportion of the ingot near or in the holder is not remelted but insteadis discarded. In this way the consumable-electrode melting step isperformed at least three times and preferably five times, withprogressive reduction in the concentration of non-metallic inclusionsand improvement in the homogeneity of their distribution, as well asfurther reduction in the content of volatile impurities. Upon eachsuccessive consumable-electrode melting these characteristics of themetal are improved, although after three such meltings most of thepossible improvement has been realized and after the fifth melting anyfurther improvement is generally insufficient to warrant the additionalsteps.

The ingot resulting from the last melting step, after appropriatecogging, cropping and conditioning may be formed into load-carryingbearing elements, such as the inner races of ball bearing assemblies.The bearing elements so made typically exhibit a fatigue life L which isat least three times that of bearings made from the original air-meltedingot and at least twice that of bearings made from material of theingot produced by the first consumable-electrode melting step abovedescribed.

Furthermore, by sectioning the final ingot and subjecting it tomicroscopic examination, it can be determined that the non-metallicinclusion content, including the number and individual size ofinclusions, is decreased by each succeeding melt, although after thefifth melt the number of inclusions is no longer greatly reduced byfurther repetition of the process.

While in the preferred embodiment of the invention the firstconsumable-electrode is in the form of a precast ingot producedaccording to standard air melting practice, in other applications of theinvention it may be produced in other ways or forms. For example it maybe provided in sponge form or as a sintered particulate body, and may beproduced by processes involving vacuum melting or induction heating.Where the invention is to be used for making bearings, the compositionof the starting material may depart substantially from that describedabove, at least some of the advantages of the invention being obtainedwith any of a large variety of compositions suitable for use inbearings. In. general, the process of the invention may be applied toany material suitable for use in consumable-electrode inert-environmentarc melting.

The following specific example further illustrates the advantages ofthis invention and is not intended to limit the scope of this invention.

A ferrous alloy having a of 3.54 was melted initially according to acommercial basic electric arc furnace Carbon 0.99 Manganese 0.30 Silicon0.38 Phosphorus 0.009 Sulfur 0.005 Chromium 1.47 Aluminum 0.006 Copper0.060 Molybdenum 0.011 Nickel .070 Vanadium 0.002 Iron Remainder Thealloy was in the form of an 18-inch diameter ingot weighingapproximately 3700 pounds. The ingot was cogged down to a diameter of 12inches, then annealed and ground. A piece was cut from this ingot androlled to 2 /2 inches round. This piece of the air-melt ingot was laterused in bearing tests described below. The remainder of the 12-inchdiameter ingot was used as the first electrode in the first melting stepof the repetitive consumable-electrode vacuum-melting process describedabove, to produce a first vacuum melt ingot 1 6- inches in diameter. Thevacuum melt ingot was then cogged to 12 inches round, annealed, ground,and a portion of the ingot removed and finished to 2 /2 inches round andused in bearing tests to be described below. The remainder of said firstvacuum melt ingot was used as a second consumable electrode in theabove-described process to produce a second vacuum melt ingot. Thesecond vacuum melt ingot was cogged to 12 inches round, then annealedand ground. A portion of the ingot was removed and finished to 2 /2inches round and used in bearing tests to be described below. A thirdvacuum melt ingot was produced in a similar manner, although no materialwas removed for bearing tests. Fourth and fifth vacuum melt ingots wereproduced similarly, except that the fourth and fifth consumableelectrodes used were 9 inches round and the resulting ingots 12" round.A 2 /2 inch diameter bar was produced from the fifth vacuum melt ingotand used in bearing tests described below.

Thirty inner rings for deep-groove ball bearing assemblies were machinedfrom each of the four 2 /2 inch bars from the air-melt ingot and thefirst, second and fifth vacuum melt ingots. The deep-groove ball bearingassemblies containing these inner rings differed only in the steps bywhich the inner ring alloy was produced, as described above. Since theinner ring of deep-groove bearing assemblies is generally the firstelement of the assembly to evidence fatigue failure, the use of bearingsin which only the inner ring is made of the material to be tested forfatigue resistance is an accepted procedure. The bearing assemblies weretested for fatigue life expressed as L under substantial load and withoil lubrication. These inner rings were identified by stamping and thenintermixed for heat treatment and final grinding. A normal quench cyclewas used, and the inner rings were tempered for stabilization at 455 F.for 4 hours. Hardness of all the inner rings was held between 60.5 and61 R The inner rings were assembled with stock outer rings and balls andsubjected to endurance testing under a radial load of 4240 lbs. perbearing.

As can be seen by reference to Table A below, listing the source of thebearing material, the test speed and the L life, the L fatigue life ofthe fifth consumable melt in this example of the invention was more than3 times that of the air-melt alloy and over 2 times that of the firstconsumable melt. Furthermore the L life of bearings made from the fifthvacuum melt is superior to any obtained by previously-known processes.

TABLE A Test Speed L10 Life Melt (r.p.m.) (millions of revolutions) 9,300 21. 7 9, 700 38.0 2nd Vacuum Melt. 9, 700 60. 0 5th Vacuum Melt. 9.300 77. 0

After the fatigue life of the inner rings had been determined, the ringswere analyzed for non-metallic inclusions, with the inclusion countsdetermined at 1000 magnification acording to the Johnson and Sewellmethod (R. F. Johnson, J. F. Sewell, The Bearing Properties of 1% C-CrSteel as Influenced by Steelmaking Practice, Journal of The Iron & SteelInstitute, vol. 196, December 1960, 414-444). The average totalinclusions observed in .0033 square inch for the inner rings from thevarious melts were as follows: air melt 102, first vacuum melt 37,second vacuum melt 23 and fifth vacuum melt 15. It is apparent that theaverage inclusion count for the lair-melt alloys was over 6 timesgreater than for the fifth melt, and the count for the first melt alloywas about 2 /2 times that for the fifth melt. The distribution of theremaining inclusions was also substantially more uniform in bearingsfrom the fifth melt than in bearings from the original air melt or thefirst vacum melt.

While this invention has ben described with particular reference tocertain embodiments thereof, it will be understood that modificationsand variations thereof can be made within the spirit and scope of theinvention as set forth in the appended claims.

What is claimed is:

1. A process for the treatment of original material of the class capableof use as the consumable electrode in consumable-electrode arc meltingin an inert environment, comprising the steps of forming a firstconsumable electrode of said material and subjecting material of saidlastnamed electrode to repeated consumable-electrode arc melting in aninert environment to form successive ingots, each of said ingots afterthe first being formed by melting of a limited portion of theimmediately-precedingly formed ingot located below the top thereof, saidoriginal material consisting substantially of the following:

Element: Percent by weight (about) Carbon 0.95 to 1.10 Chromium 1.30 to1.60 Manganese 0.25 to 0.45 Silicon 0.20 to 0.35 Phosphorus Up to 0.025Sulfur Do. Aluminum Up to 0.015 Copper Up to 0.060 Molybdenum Up to0.020 Nickel Up to 0.080 Vanadium Up to 0.003 Iron Remainder.

the respective amounts of the elements almuinum, copper, molybdenum,nickel and vanadium present in said alloy being such as to provide avalue of not greater than about 3.5 in the formula:

Al Cu Mo Ni V 0.015 0.060 0.020 0.080 0.003

Where the element symbols Al, Cu, Mo, Ni and V represent the percent byweight of each such element present in said alloy.

2. The process of claim 1, in which said original material consistssubstantialy of about 0.010% aluminum, up to about 0.050% copper, up toabout 0.015% molybdenum, up to about 0.055% nickel and up to about0.002% vanadium, and wherein said value of 4 is not greater than about3.0.

3. A process for the treatment of a body of metal including metalalloys, to reduce the number of non-metallic inclusions therein and toimprove the homegeneity there of, comprising: forming from said body ofmetal a first consumable electrode; melting said electrode in an inertenvironment by a consumable-electrode process to form a first ingothaving peripheral non-metallic regions and having other portions of lownon-metallic inclusion content; using a portion of said first ingot oflow non-metallic inclusion content as a consumable electrode in aninertenvironment consumable-electrode remelting process to form fromsaid portion a second ingot having peripheral non-metallic regions andhaving other portions of low non-metallic inclusion content; and,starting with said second ingot, sequentially performing a plurality ofconsumable-electrode inert-environment remeltings in which theconsumable-electrode melted in each of said plurality of remeltingsconstitutes the first-solidified portion of the immediately-precedinglyformed ingot; said first consumable electrode consisting essentially ofthe following elements in the following percentages by weight:

Element: Percent by weight Carbon About 0.95 to about 1.10. ChromiumAbout 1.30 to about 1.60. Manganese About 0.25 to about 0.45. SiliconAbout 0.20 to about 0.35. Phosphorus Up to about 0.025. Sulfur Do.Aluminum Up to about 0.015. Copper Up to about 0.060. Molybdenum Up toabout 0.020. Nickel Up to about 0.080. Vanadium a- Up to about 0.003.Iron Remainder.

the respective amounts of the elements, aluminum, copper, molybdenum,nickel and vanadium present in said alloy being such as to provide avalue of not greater than about 3.5 in the formula:

A Cu Mo Ni v 0.015 0.060 0.020 0.0s 0.00s

Where the element symbols Al, Cu, Mo, Ni and V represent the percent byweight of each such element present in said alloy.

4. The method of fabricating a metal alloy having increased resistanceto fatigue when used as a rolling bearing element, comprising: forming afirst consumable electrode of a metal alloy having essentially thefollowing the respective amounts of the elements aluminum, copper,molybdenum, nickel and vanadium present in said alloy being such as toprovide a value of 5 not greater than about 3.5 in the formula:

Al Cu Mo Ni 0.015 0.060 0.020 0.080 0.003 where the element symbols Al,Cu, Mo, Ni and V represent the percent by weight of each such elementpresent in said alloy; melting said electrode in an inert environment bya consumable electrode process to form a first ingot; subjecting thelower portion of said first ingot to consumable-electrode remelting inan inert-environment to form a second ingot; and, starting with saidsecond ingot, sequentially performing a plurality ofconsumable-electrode inert-environment remeltings in which the portionof the consumable electrode melted in each of said plurality ofremeltings is derived from the lower portion of the immediatelyprecedingly-formed ingot, thereby to produce an ingot havingsubstantially said composition but significantly increased resistance tofatigue.

5. A process for fabricating a rolling bearing element of improvedfatigue resistance, comprising: forming of I an original body of metal,a first consumable electrode; melting said electrode in an inertenvironment by a consumable electrode process to form a first ingothaving peripheral non-metallic regions on the sides thereof; separatingsaid non-metallic regions from the remainder of said first ingot; usingthe lower part of said. first ingot after said separation ofnon-metallic regions as a consumable electrode in an inert-environmentconsumable-electrode remelting process to form a second ingot havingperipheral non-metallic regions on the sides thereof; separating saidlast-named non-metallic regions of said second ingot from the remainderthereof; starting with said remainder of said second ingot, sequentiallyperforming a plurality of alternate consumable-electrodeinert-environment remeltings and peripheral non-metallic regionseparations, in which the consumable electrode for each of saidplurality of remeltings is derived from the lower portion of theimmediately precedingly-formed ingot after separation of peripheralnon-metallics therefrom; and forming at least a part of the lowerportion of the ingot produced by the last remelting into arolling-bearing element; said original body and said last-named partboth consisting essentially of the following:

Element: Percent by weight (about) Carbon 0.95 to 1.10 Chromium 1.30 to1.60 Manganese 0.25 to 0.45 Silicon 0.20 to 0.35 Phosphorus Up to 0.025Sulfur Do. Aluminum Up to 0.015 Copper Up to 0.060 Molybdenum Up to0.020 Nickel Upto 0.080 Vanadium Up to 0.003 Iron Remainder.

the respective amounts of the elements aluminum, copper, molybdenum,nickel and vanadium present in said alloy being such as to provide avalue of 5 not greater than about 3.5 in the formula:

Al Cu M0 Ni V 0.0l5 0.060 0.020 0.080 0.003

Where the element symbols Al, Cu, Mo, Ni and V represent the percent byweight of each such element present in said alloy.

References Cited UNITED STATES PATENTS 3,067,473 12/1962 Hopkins3,235,373

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,541,321 September 12 1967 Thomas W. Morrison et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 4, line 25, in the equation, for

M0 read MO 0 040 D 020 column 5, line 9, strike out "steel".

Signed and sealed this 24th day of September 1968.

testing Officer Commissioner of Patents

1. A PROCESS FOR THE TREATMENT OF ORIGINAL MATERIAL OF THE CLASS CAPABLE OF USE AS THE CONSUMABLE ELECTRODE IN CONSUMABLE-ELECTRODE AARC MELTING IN AN INERT ENVIRONMENT, COMPRISING THE STEPS OF FORMING A FIRST CONSUMABLE ELECTRODE OF SAID MATERIAL AND SUBJECTING MATERIAL OF SAID LASTNAMED ELECTRODE TO REPEATED CONSUMABLE-ELECTRODE ARC MELTING IN AN INERT ENVIRONMENT TO FORM SUCCESSIVE INGOTS, EACH OF SAID INGOTS AFTER THE FIRST BEING FORMED MELTING OF A LIMITED PORTION OF THE IMMEDIATELY-PRECEDINGLY FORMED INGOT LOCATED BELOW THE TOP THEREOF, SAID ORIGINAL MATERIAL CONSISTING OF SUBSTANTIALLY OF THE FOLLOWING: 